This invention relates to a thermoplastic elastomer composition, the flexibility and compression set of which has been improved without impairing the abrasion resistance.
Thermoplastic polyester elastomers are multi-block copolymers having, in the polymer main chain, polyester-and polyether-recurring units or polyester-and polyester-recurring units, and are excellent in mechanical properties, heat resistance and oil resistance.
The thermoplastic polyester elastomers have such excellent characteristics, but have such drawbacks that the hardness is high and the flexibility is poor. In addition, they have a large compression set, so that their use in wider applications has been restricted.
In order to solve these problems, there has been provided a thermoplastic elastomer, the flexibility and compression set of which have been improved by blending a rubber component, and the thermoplastic elastomer is suitable as a material for automobile parts, particularly for joint boots.
However, since the above thermoplastic elastomer is flexibilized by blending a rubber component therewith, it is particularly inferior in abrasion resistance and such a further problem is caused in some cases that the molded articles of the thermoplastic elastomer are worn by being rubbed with one another or with other parts and finally become unusable.
In particular, when the molded articles are used in joint boots, there is such a problem that the bellow portions thereof are rubbed with one another to be broken.
As mentioned above, thermoplastic polyester elastomers are excellent in mechanical properties, heat resistance, oil resistance and the like; however, when a rubber component is blended therewith for improving the flexibility and compression set thereof, such new problems are caused that the abrasion resistance is lowered and when molded articles thereof are rubbed with one another or with other parts they are broken.